High-frequency tuner device



July 4, 1950` c. F. FREY, JR., x-:rAL 2,513,393

HIGH-FREQUENCY TUNER DEVICE Filed March 29, 1949 LJ' IN VEN TORS TTORNEY Patented July 4, 1950 HIGH-FREQUENCY TUNER DEVICE Cleon F. Frey, Jr., Greenfield, and Robert J. Aust, Indianapolis, Ind., assignors to P. R. Mallory & Co., Inc., Indianapolis, Ind., a corporation of Delaware Application March 29, 1949, Serial No. 84,222

(Cl. Z50- 40) 14 Claims.

` This invention relates to a tuner and particularly to one of the type suitable for high frequency electromagnetic carrier wave signals in the megacycle range.

Heretofore, attempts have been made to tune televisionreceivers and receivers of the frequency modulation type by adjusting the capacitance and inductance of resonant circuits. This arrangement is not particularly suitable for tuning high frequency circuits operating in the megacycle range since for slight changes for frequency the inductance effect of the concerned components of the electrical circuits becomes a predominating factor.

Also, television receivers and receivers of the frequency modulation type have been tuned to any selected'video or broadcast channel or station by the selective switching of either an inductance or capacitance, or both into a circuit or circuits to be resonated. Provision for Vernier tuning of each channel was made by having a separate trimmer control disconnected from the conventional video channel selector. Therefore, it can be realized that a compact tuner for either television'or high frequency electromagnetic carrier wave signals was unattainable heretofore. Further, satisfactory Vernier tuning of the above mentioned receivers by the operators thereof really did not exist since the trimmer controls were usually placed either in the rear of the receivers or within the chassis thereof for manipulation by servicemen or skilled technicians at the factory where these receivers were built or assembled.

The ideal manner of tuning either a television receiver or an FM receiver would involve changing only the inductance of the resonated circuits. In connection with the tuning of a television receiver operating under the present distributive arrangement of carrier wave channels a substantial band spread of frequency is found between one group of channels and another. For instance, channel 7 is designated as operating at a frequency of 176 megacycles while channel 6 operates at a frequency of 88 megacycles, thus producing a so-called "dead range of 88 megacycles. Heretofore, known timers could not skip this so-called dead range without the use of conventional switching.

Therefore, a primary feature of this invention is the elimination of the inadequacies of prior high frequency tuners.

A further object of the present invention is t provide a compact tuner adapted for linear tuning of circuits operating on frequencies in the megacycle range.

Another object of this invention is to provide a tuner adapted for tuning a high frequency circuit operating on a band of frequencies in which one group thereof is widely separated from another group by a so-called dead range.

An additional important object of this invention is to provide a tuner for high frequency signals in which a Vernier effect is provided when the tuner is being used on either the high or lower ranges of said high frequency signals.

A further object of this invention is to provide a tuner in which the effect of an absorption device is augmented by the Vernier effect produced by slight changes in an inductance which may have the form of a metallic strip.

Another object of this invention is t0 provide a. tuner in which an inductance is given such form as to provide linear tuning of a circuit operating at least within about the region of megacycles.

An important object of the present invention is to provide a high frequency tuner adaptable either for television receivers or receivers of the frequency modulation type.

A further object of the invention is to provide a tuner in which an adjustably shaded single coil is so arranged with a conductor that the coil may be used for rough tuning in predetermined positions of a shading means and for fine tuning in other predetermined positions thereof, the fine tuning being also augmented by a Vernier effect of said conductor.

An important object of this invention is to provide a tuner having both coarse and line tuning, the ne tuning being effectively divided into two forms thereof.

Another object of this invention is to provide a high frequency tuner with accurately aligned components.

Other objects of the invention will be apparent from the following description `and accompanying drawings taken in connection with the appended claims.

The invention accordingly comprises the features of construction, combination of elements, arrangement of parts, and methods of manufacture referred to above or which will be brought out and exemplified in the disclosure hereinafter set forth, including the illustrations in the drawings, the scope of the invention being indicated in the appended claims.

For a fuller understanding of the nature and objects of the invention as well as for specic fulfillment thereof, reference should be had to the following detailed description taken in connection with the accompanying drawings, in which:

Figure l is a front view of one embodiment of a tuner mounted on a base member in accordance with the present invention;

Figure 2 is a section along the line 2 2 of the tuner shown in Figure l;

Figure 3 is another section along the line :3*3

of the tuner shown in Figure 1;

Figure 4 is a front view of the tunel` devoid of the movable elements thereof; n

Figure 5 is a section along the line 5-5 of the tuner, Figure 1 showing in an enlarged fragmentary View the details of the shading coil blade correlated with the bridging portion `of 'a contacter, and of the connection between a lumped inductance in the form of a spiral coil and at least two other inductances in segmental form; and

Figure 6 is a Aschematic of the electrical circuit of the tuner shown inthe above figures.

According to one phase of this invention a tuner for high frequency application such as in a television receiver or a receiver of the frem quency modulation type, comprises a conductor or metallic segment Yof tapered form which is contacted 'by -a slidable 'contacter for the purpose ,efcontinuously varying the frequency of a receiver in a linear fashion over a considerable range of frequencies such as, for instance, between the limits of 176 vInegac'ycles lto 216 megacycles. 'This tuning action takes place without any intermediate switch action of the contacter. In another .phase of this invention a tuner for a television receiver or similar device operating on high frequency .contemplates the use of a xe'd coil such as a spirally wound coil interposed between the above named segment and another .segment preferably having a uniform cross section. This 'c'oil acts a's a lumped inductance for facilitating the bridging of a so-called dead range in the present television broadcast chan- .nels or, for that matter, any dead 'range within any type of broadcast system. In 'still another phase of this invention a shading coil `means is .-provided whereby, when `it -is properly oriented with a contact and said segments, the tuning transition from the 'television channels corresponding to the -high band group of frequencies to vthe channels corresponding 'to the low band ygroup of frequencies may be made Awitha minimum movement of the contact while accomplishing coarse tuning 4of thelow band channel nearest said transition. The 'shading coil means acts both as coarse and finetunin'g means for each channel selected inthe low band group, dependent upon the degree of off-tune produced bythe initial setting of said means for the selected channel, the uniform segment acting as an additional and more fine Vernier. When the comparatively low `band end 'of the low band frequency group is concerned, 'the coarse tuning `produced by 'the shading means `is minimized. Continuous tuning of both the low and high band groups of high yfrequency Vchannels is obtained 'by the present invention. v L Broadly stated with reference to Figures 1 5, Vthe tuner for a circuit to be-re'sonated in response 4'to signals from a radiant energy source transu mitting at 'least vtwo frequency spaced groups of signals, each group representing a number 'of channels, comprises means including at least one tapered conductor or segment ill and a'contactor `I"I for continuously and linearly tuning this circuit to a relatively high frequency band of signals in one channel group. This tuner also contains additional means including a conductor or segment I2 contactable by the contacter Il and a coil I3 coupled to a low frequency portion I4 of the tapered conductor I ll for tuning the circuit to a relatively low frequency band of signals in the other channel group. The conductors I0 and I2 are separated by an air gap I5 correlated with a dead range of signals producing the spaced groups of channels.

rChe additional means associated with a low band side tuning of the tuner includes an eddy current blade I6 connected to the contactor II. This means is so constructed and arranged that the coil I3 is shaded to produce maximum eddy currents in the blade I 6 during the interval of changing the operating characteristics of the circuit required from one channel group to another, one channel group being specifically frequencies between 176 megacycles to 216 megacylces while the other group corresponds to frequencies between 88 and 44 megacycles. However, it should be understood that the concept of this invention is not to be limited to the broadcast channels given above or the named frequencies associated with each of the segments or sectors such as I0 and I2, Vernier tuning on lowest channels is avoided.

The contactor II comprises an arched metallic spring I8 adjustably bolted to a frame member I9 containing a C-clamped portion 20 surrounding an insulative shaft 2l inserted through a central opening 8 of the base member I'I. The vouter end of the spring I8 contains a semi-ball shaped contact 22 of such dimensions as to bridge the air gap I5 when it is desired to transfer the contactor I8 from segment I0 to segment I2 or vice versa. The inner end of the springlike contact It is also formed in a manner similar to the contact 22 for slidably engaging a central contact ring 24 mounted on the base I1 and -connected to a terminal member 25 of the conductor I2 through ya conductive strip 26. A bolt and nut v2" connects vthe 'spring IB to the vrotata- -ble frame I 9 to provide lateral Aadjustment to the contacter II relative to ,the shading .coil .blade I6. VvAlso Vit will be noted that the blade- I5 may lbe adjusted `:angularly with respect to the contactor II :by virtue of the slot 28 within a protruding portion 29 of the lblade I5. Of course such angular adjustment cannot take place until the lbolt `Sil on the C-clamp 20 as well vas the bolt and nut 21 is loosened.

The means for holding the segments VIl) and I2 to 'the insulative base member I1 are shown as screws 3I threaded .into the base member and selected :portions of the respective segments.

fIn `the 4present invention the connection between the inner end 34 of coil I3 and the low band end I4 of the tuning strip ID is made bya separate vconductor 35 carried through an opening 36 of -the base member I-'I across the back of the coil I3 and then led through another opening 37! in lthesame base member for connection to an inwardly protruding lug v38 of conductor I0. The outer turn 39 of the coil I3 can be similarly connected to the linwardly protruding vportion 40 adjacent the high band end 4I of segment I2.

Segments I and I2 with their terminals 25 and 33 may be stamped from a single sheet of metal, severable webs of thin material connecting the segments .being leftso as to make .it easy to 'align the segments with the printed coil I3 on the 4base I'l. After the segments I 0 and I2 are fastened to the base I1 by screws 3|, the webs may be severed. The ring 24 and connective strip 26 may also be formed integral with segments I0 and I2. It is also within the purview of this invention to stamp and adhere the segments I0 and I2 with connective terminals and strips to the base I'I in one machine operation. However, the preferred method of forming the above mentioned segments, strips, rings, etc. is by printing them directly on the ceramic base I'I.

Referring to Figure 6 of the drawing, the electrical circuit of the tuner of the subject invention is shown schematically so as to more easily demonstrate the novelty of the present tuner from the electrical viewpoint only. In Figures 1 and 4 the terminal means 25 and 33 are labeled respectively "L. T. for low terminal and I-I. T. for high terminal and this marking is followed in Figure 6. In Figure 6 an arrow A in a continuous line corresponds to the contactor II in its present position in Figure l. It will be noted that segment I2 is shunted by the contactor I I corresponding to said element A of Figure 6 through the connection labeled B to the L. T. side of the tuner. responds to the combination of ring 24, terminal 25 and the connective strip 2B interconnecting the two. In Figure 6 the mechanical connection between the shielding means I 6 and the conta ctor I I is shown by the dotted line C connected to the solid arrow D corresponding to the absorption blade or eddy current blade I5. The angle between the joined center lines of contactor II and blade I 6 respectively is indicated as X in Figure 6. The segment III is marked E and the segment I2 is marked F, both being interconnected by the coil I3 labeled G in the electrical circuit.

In the operation of the novel high frequency tuner band spreading may be involved. but in one version of this invention it may not. The condition is taken in which it is desired to tune a television receiver to channel 13 corresponding approximately to a position of the contactor I I by the dotted line H of Figure l and to the H position of the contactor A in Figure 6. Since channel 13 represents a frequency of 216 megacycles, very little or perhaps none of the length of the segment will be required to tune the television receiver if the length of the terminal means 33 and 25, and also including the connective means ZI'and 26 to the contactor II is such as to produce the proper matching inductance and capacitance of the circuit to be resonated at that frequency. However, for the present showing, some length of the segment ID is included in the electrical circuit operating on channel 13. Let us suppose that the operator wishes to tune the receiver to some lower frequency. He would turn the shaft 2! in a clockwise direction from the rst position marked I-I to some pre-selected point on the high band segment I0. This predetermined point is reached very easily since the contour or the cross sectional shape of the segment Iii from the high band end marked 50 to the low band end I4 is such that for a linear movement of the contactor II a linear change in the frequency of the resonated circuit in the television receiver is produced. It is to be pointed out at this time that while the segment I0 is shown as approximately a half-ring, it may assume a different form and be of such length that linear tuning of high frequencies may extend over a wider band of frequencies than that heretofore indicated. Segment I0 may also be con- The connection B corf able for mass production.

structed for non-linear tuning. It may be said that the frequency tuning range would be limited by feasible commercial structures in which the factor of minimum lead length is attained. The concept for one phase of this invention, therefore, is to produce linear tuning of a high frequency circuit in the manner given above.

Assuming now that it is desired to tune the television receiver to channel 6, corresponding to a frequency of 88 megacycles, which related to the tuner structure would be located near the high band lportion 4I of the low band segment I2, very close to air gap I5. For practical purposes channel 7 is indicated on the left side of the air gap I5 and channel 6 is on the right side of the same air gap. Therefore, in order to switch from channel 7 to channel 6, a limited movement of the contactor II determined by the width of the air gap I5 is required. Looking at Figure l, the contactor shows contact 22 bridging the air gap I5 and also shows the spiral coil I3 shaded by blade I6. The blade I6 and the contactor II are so oriented with respect to each other that when the contact 22 is about to transfer its contact from segment III to segment I2, the inductance of the coil I3 will simultaneously undergo a maximum change and thereby facilitate a transition of timing of the television receiver from channel 7 to channel 6 with a very small movement of the shading blade I6 and of the associated contactor II. Continued movement of the shaft 2I in a clockwise direction through a predetermined angle produces a vernier tuning action of the contact 22 in slidable contact with the segment I2 bechannels are dependent a great deal upon the specic form of the shading blade I5 and upon the size and location of the spiral coil I3 with respect thereto shown by the angle X of Figure 6, and with respect to the low band tuning segment I 2. However, it can be recognized that linear tuning may be accomplished by the proper design. of the shading blade I t and the correlated lumped inductance I3.

From the present invention a compact, simple. and inexpensive television tuner of reliable construction is indicated since but one coil I3 representing a lumped inductance can be printed, stamped, or otherwise formed upon an insulative backing member and strip conductors of predetermined form can be stamped on this backing or preformed for mounting thereto with the proper orientation with respect to the flat or pancake type coil. The fixed parts of the tuner can be produced in a manner particularly suit- It is recognized that the art of printing a coil en an insulative base is old as well as the forming of a stamped conductor. However, the particular organization of a high frequency tuning segment constructed for continuous or switchless linear tuning with or without a segment suitable for relatively low band tuning wherein the latter is used as a Vernier is novel in every phase thereof. The means for contacting both the high and low fre- 75 quency segments of the tuner are also of very simplev constructionand taken: in connection Withthelnovel tuning transition meansincluding: thel shading` bladeV disclose another important' plias'e of the invention.

While the presenty invention, as.v` to its objects and advantages, has been described herein as carried out inv speciiic embodiments thereof, it is not desiredto be limitedV thereby but it is intendedto cover the inventionbroadly Within the` spirit and scope of theappended claims.

What is claimed is:

l'. A tuner for hignfrequencysignals covering a substantial band'comprising a lumped inductance, atleast one inductance in strip forni coupled thereto, means including a movable con tactor for'conducting said signals tosaid' induct-v ances, and' shading means coupled t'o'said con.- tact'or and soconstructed'and arranged with're spect to said lumped inductance that for contactlposition of said contacto-r'contiguous'to 4saidl coupling of said inductances theabsorption ef'n feet of` shadingv .means on' saidl lumped in ductance isl very high, continued movement of said contacter away from said-lumped induct-Y anceeand in contactvvith said'distrlbuted inducteance causinga gradually increasing inductive effect of said lumped inducta-nce sensitively-tofbev augmented by that portion ofl said'strip induct ance increasingly included with said lumped in ductance.

2. Ai tuner forhigh frequency signals coveringa substantial band comprising alumpedinductn` ance, atleast one distributedinductance. coupled. thereto, means includingA av movable contactor: for. conducting said signals to saidinductances, andl shading means coupled-to said. contactor and` so constructed and arranged with respect to saidu lumped inductance that for a contact positionof saidfcontactor. contiguous to said'coulpling of, said. inductances'theabsorption effect of said shading means on said lumped inductance is armaximum ccntinuedmovement of said contactor away: from said lumped inductance and incontact with saiddistributed inductance:` causing' a i gradually increasingy inductive effect of saidv lumped inductance sensitively'to be augmented by that portion of' said distributed inductance increasingly in cluded'with said lumped inductance.

3. A- tuner for a circuit to be resonated. infresponse-to signals from a radiant energy source transmittingl at least tWo separated groups of frequency signals, eachgroup representing a` number of channels carrying at leastvideo-signais; comprising means'including at least one tapered conductor and a contactor'for'continuously and linearly tuning said circuit to a relatively highfrequency band of signals'in one said channel group; and ad\.'iitionalr means including both a conductor contactable-bysaid contactor and a' coil coupled to a lowV frequency portion of said tapered conductor for' tuning saicl-V circuit'to a relatively low frequency band of signals in the otherchannel group; said conductors being'sepa rated by'an air gap correlated with a dead range of signals producingsaid groups'of channels, said additional means including any eddy currentV blade coupled to said contactor and so constructed and arranged'that said coil is shadedv to' produce substantial eddy currents in said blade during the interval of changing the operating characteristics of said circuit required from one.Y channel group to' another.

4'. A tuner comprising a rst conductor havingoneend thereof' adapted to. be connected to a source-of radiant energy; Saidv conductor having a. surface of v tapering; form from said.` end` to:V arr opposite-end;` aspiral Winding having one.l end' thereof coupled to an opposite end of said corr-V ductor; a secondvcond'uctor having one end-coupled to an opposite end of said spiral, rotatable' means having a portion for electrically contact ing said first' and second conductors, shading means coupled to saidportion of' said rotatable means, `said shading means being so constructed and arranged with respect to said'conductors and rotatable means that a maximum effect of said shading means upon the inductance of said spiral winding is producedl simultaneously with the transfer of contact of said portion from said'rst` conductor to saidsecond conductor, and'meansF coupling said portion of the rotatable means andE afree end portion of said second conductorl to said source of energy.

5. A tuner adapted for a circuit operating on a Wide band of high frequency electromagnetic signal waves comprising a xed conductor of angular form, a nxedcurved conductor spaced from' saidA conductor, said conductors forming a substantially enclosed area, a lumped inductance, iixedly interposed between said conductors, and" means including a combined rotatable contactor. and an absorption, arrangement adapted to. affect said. lumped inductance and for changing` the inductanoe of said conductors during the rotation of said contactor, said contacter when ini contactwith saidY curved conductor. actingas a Vernier during the time saidabsorption arrangement is effectively coupled to said lumped, inductance.

6. A tuner for high frequency signals covering a substantial band. comprising a lumped inductance, a distributed inductance coupled thereto, means including a movable contactor for conducting saidfsignals to said inductances, shading means coupledY to said contacter and so constructed and varranged with respect to said lumped inductance that for, a contact position ofv said contactor contiguous to said coupling of saidj inductances the absorption effect-of said shading. means onsaid lumped inductance is.a maximum,. movement of said contactor away from saidv lumped inductance-,and in Contact Withsaid distributedinductance causing a gradually increasing inductive effect of.y said lumped` inductance sensitively to beaugmented by that portion` of.. said. distributed inductance included with said lumped. inductance, .and means for. adjusting said shading means relativel to said lumped inductance and said contacterv whereby signaltracking is facilitated.

7; Altuner` comprising a high-frequency-bandV sectorof taperedforni, a low frequency bandsector ofu uniform cross section, said sectors being arrangedto form a substantially closed area, thedirectly opposedendsof said sectors adiacent'the lowelfrequency portion of said tapered sector^ being Yseparated a predetermined distance cor,- relatedfwiththe so-called dead rangel in broad-- cast channels, a. coil interconnecting said opposed ends, terminal, means for connecting the remaining end of each of said sectors to-asource of radiantenergy, means including a rotatable contactor for-providing a shunt path around'at leasta-portion of said interconnected sectors dependent on the position of said contactor, and a shading coil blade coupled to said contactor and. so constructed and arranged with respect thereto and said coil thatf-atuning` transition through said. deadf range is obtained when said'contac` tor is substantially transferred from one of said sectors to another.

8. A tuner comprising a first flat metallic member having one end thereof adapted to be connected to a source of radiant energy, said member having a diminishing cross section from said end to an opposite end,.a printed flat winding having oneend thereof coupled to said opposite end of the sector, a second at metallic sector having one end coupled to an opposite end of said winding, rotatable means including an adjustable contact for slidably engaging said first and second sectors, shading means coupled to said rotatable means-said shading means being so constructed and arranged with respect to said sectors and rotatable means that a maximum effect of said shading means upon the inductance of said winding is produced simultaneously with the effective transfer of contacting action of said rotatable means from said first sector to said second sector, and means coupling said rotatable means and a free end portion of said second sectorto said source of energy.

9. A tuner comprising a rst metallic sector having one end thereof adapted to be connected to a source of radiant energy, said sector having a surface of tapering form from said end to an opposite end, a spiral winding having one end thereof coupled to said opposite end of said sector, means for contacting said rst and second sectors, means for effecting relative movement between said contacting means and said sectors, shading means coupled to said rotatable means, said shading means being so constructed and arranged with respect to said sectors and rotatable means that a maximum effect of said shading means upon the inductance of said spiral winding is produced simultaneously with the effective transfer of contact of said rotatable means from said first sector to said second sector, means coupling said rotatable means and a free end portion of said second sector to said source of energy, and means for adjusting said shading means relative to said rotatable contacting means and with respect to said winding in said transfer position of the contacting means whereby effective tracking over the operating range of said second metallic sector is accomplished.

10. A tuner for a circuit operable in response to high frequency radiant energy including Video signals comprising fixed high frequency current conducting means a portion of which is tapered, xed relatively low frequency conducting means, said latter means including a curved conductor of less than one turn aligned with but separated from the low band end of said tapered portion of said conducting means by a gap, said ixed conducting means being respectively coupled together by a portion of said low frequency conducting means, and shunt means including angularly movable contacting means for shunting predetermined high frequency signals away from said low frequency conducting means, said shunt means including a coil shading device coupled to said contacting means and so constructed and arranged as to shade at least a portion of said low frequency conducting means during the tuning of said circuit to relatively low frequency signals, said latter signals carried by both said conducting means including at least the lowest frequency band of said video signals.

11. A tuner comprising a base member, a tapered conductor xed to said member and adapted to produce continuous linear tuning of a circuit subjected to relatively high frequencies,

another conductor xed to said base member and having an end spaced from the smaller end of said tapered conductor in opposite relation, a flat spiral coil fixed to said member adjacent said opposite ends of said conductors, one end of said coil being connected to one end of said opposite conductor ends and the other coil end being connected to the other one of said opposite conductor ends, and a combined contactor and coil shading blade device movably mounted in said base member, said contactor being constructed and arranged to contact both said conductors during a minimum relative movement thereof including the bridging of said conductors, said shading blade being constructed and arranged for movement near said coil to produce no electrical effect upon said tapered conductor but a maximum change in the inductance of said coil substantially at the time said contactor bridges said conductors whereby said circuit is tunable over a spectrum of frequencies widely separated by a so-called dead range without significant lost motion of said combined contactoland shading blade, continued movement of said blade spaced over said coil producing a gradual change in the inductance thereofpwhereby said circuit is tunable to a lower band of said frequencies.

l2. A tuner for a circuit responsive to relatively high frequency signals from a radiant energy source, comprising a high frequency band sector of tapered form and an aligned low frequency band sector formed from a single piece of conductive material, a backing member for said sectors, said sectors being joined by at least one web severable therefrom after mounting on said member to produce at least one gap corresponding to a distinct tuning transition point, a coil having at least one turn mounted on said member and electrically connecting an end of one of said sectors formed by said web severance to an end of the other sector likewise formed to produce a continuous conductor, means including a rotatable contacter and a shading coil blade mounted on said backing member for electrically shunting at least a portion of said continuous conductor dependent upon the divergence of the frequency to which said circuit is tuned from a predetermined reference signal, and means for coupling said continuous conductor to said source, said shading coil being so shaped and correlated with said contactor as to be effective to gradually alter the inductance of said coil only in predetermined positions of said contacter on said low band sector, the maximum change of inductance of said coil being produced during the period of said contactor bridging said gap whereby said tuning transition point is effected.

i3. A tuner for tuning a circuit to frequencies separated by a so-called dead range comprising a tapered metallic sector having one end thereof representing the high portion of said frequencies adapted to be connected to a source of radiant energy, a uniform metallic sector aligned with said tapered sector and having one end thereof spaced in opposed position from an end of said tapered sector remote from said high frequency portion thereof, a flat spiral coil arranged within an area substantially enclosed by said sectors and adjacent said spaced ends, means connecting the ends of said spiral to said opposed ends of the sectors to produce a continuous conductor including said sectors, the end of said uniform sector remote from said coil being connected to said source of radiant energy, mounting means for said sectors and coil, a combined f'contactor and `eddy current blade unit insulatlvely and rotatively arranged on said mounting means, vsaid contactor being adapted to `contact Je'oth said sectors during less than one turn of said unit, said blade being so constructed and ar- :ranged with respect to ysaid sectors Aand said coil that a maximum inductance canceling eiect is produced as said contacter bridges said sectors, continued rotation of said unitaway from said 'tapered sector producing uniformally less in- Eductance canceling effect Vto a nal vnegligible ef- .fect at the lowest frequency, and means connecting said unit to the power connected end of said `uniform sector.

14. 'In a tuner for a circuit energized by high frequency signals in at least two widely separated groups vof radiant energy broadcasting channels, 'the combination comprising at least two curved conducting members having severable webs therebetween and formed from a single piece of material, each of said members including an integrally formed terminal at eachend thereof, in'- sulative support means for said members-,one of said webs when severedicreating a space between said members designated as a dead signal range, a coil mounted on said support means adjacent .12 said space and electrically interposed Abetween said members through the integrally V.formeclterlr'n'inals near said space, one of said curved members having such :changing sectional form throughout its length as to be adapted vfor tun*- ing said circuit to a high frequency band of signals, the other curved member being 'substantially uniform, an angularly movable contacting device adjustably mounted to said support means in -a centralized position with respect to said members, fixed conductive means including a :portion in a slidable contact-relation with a .portion 'of said contacting device and interposed between an en'd o'f said other pair of members remote from said space and said device, and -an absorption plate coupled V'to said device in a predetermined spaced arrangement with respect to A'said coil when said contact device is in a position t'o bridge said members, 'said plate being of .such io'rrn as to substantially cover 'a major surface of said coil in said contacter position. I

CLEON F. lFREE?, JR.

ROBERT J. AUST.

No references cited. 

